Known methods of measuring the mass flow distribution of a flow over a measuring plane use sensors which are inserted into the flow and there, at certain points, measure the local mass flow. For measuring the mass flow distribution over the entire plane, all points must be approached by the sensors. By this method it is not possible to measure temporary mass flow distributions over the entire plane or even over partial areas of the measuring plane. In addition, the insertion of the sensors into the flow must result in an undesired modification to the flow.